Join the conversation on IDNLearn.com and get the answers you seek from experts. Ask your questions and receive reliable and comprehensive answers from our dedicated community of professionals.

The following rational equation has denominators that contain variables.

For this equation:
[tex]\[ \frac{9}{7x+21} = \frac{9}{x+3} - \frac{6}{7} \][/tex]

a. Write the value or values of the variable that make a denominator zero. These are the restrictions on the variable.

b. Keeping the restrictions in mind, solve the equation.

a. What is/are the value or values of the variable that make(s) the denominators zero?

[tex]\[ x = \][/tex]

[tex]\(\boxed{\text{Simplify your answer. Use a comma to separate answers as needed.}}\)[/tex]


Sagot :

To solve the given equation, we need to address two parts: finding the restrictions on the variable and solving the equation while keeping these restrictions in mind.

Part a: Finding the restrictions on the variable

The given equation is:
[tex]\[ \frac{9}{7x + 21} = \frac{9}{x + 3} - \frac{6}{7} \][/tex]

First, we need to determine the values of [tex]\(x\)[/tex] that cause the denominators to be zero.

1. For the denominator [tex]\(7x + 21\)[/tex]:
[tex]\[ 7x + 21 = 0 \][/tex]
Solving for [tex]\(x\)[/tex]:
[tex]\[ 7x = -21 \][/tex]
[tex]\[ x = -3 \][/tex]

2. For the denominator [tex]\(x + 3\)[/tex]:
[tex]\[ x + 3 = 0 \][/tex]
Solving for [tex]\(x\)[/tex]:
[tex]\[ x = -3 \][/tex]

So, the value of the variable that makes the denominators zero is [tex]\(x = -3\)[/tex]. This is a restriction on the variable because at [tex]\(x = -3\)[/tex], at least one of the denominators becomes zero, which would make the expression undefined.

Restrictions:
[tex]\[ x = -3 \][/tex]

Part b: Solving the equation

Next, we solve the equation while keeping the restriction [tex]\(x \neq -3\)[/tex] in mind.

The equation to solve is:
[tex]\[ \frac{9}{7x + 21} = \frac{9}{x + 3} - \frac{6}{7} \][/tex]

First, simplify the left-hand side and the right-hand side of the equation.

Left-hand side:
[tex]\[ \frac{9}{7x + 21} \][/tex]
Factor the denominator:
[tex]\[ 7x + 21 = 7(x + 3) \][/tex]
So,
[tex]\[ \frac{9}{7(x + 3)} \][/tex]

Right-hand side:
[tex]\[ \frac{9}{x + 3} - \frac{6}{7} \][/tex]

To solve this equation, let's first eliminate the denominators by finding a common denominator. The common denominator is [tex]\(7(x + 3)\)[/tex].

Multiply every term by this common denominator:
[tex]\[ 7(x + 3) \cdot \frac{9}{7(x + 3)} = 7(x + 3) \cdot \left(\frac{9}{x + 3} - \frac{6}{7}\right) \][/tex]

This simplifies to:
[tex]\[ 9 = 7 \cdot 9 - 6(x + 3) \][/tex]

Simplify the right-hand side:
[tex]\[ 9 = 63 - 6(x + 3) \][/tex]
[tex]\[ 9 = 63 - 6x - 18 \][/tex]
Combine like terms:
[tex]\[ 9 = 45 - 6x \][/tex]

To solve for [tex]\(x\)[/tex], isolate [tex]\(x\)[/tex]:
[tex]\[ 9 - 45 = -6x \][/tex]
[tex]\[ -36 = -6x \][/tex]
[tex]\[ x = 6 \][/tex]

Valid solution:
We must ensure that our solution [tex]\(x = 6\)[/tex] does not violate the restriction [tex]\(x \neq -3\)[/tex]. Since [tex]\(x = 6\)[/tex] is not in the restricted values, it is a valid solution.

Answer:
[tex]\[ x = 6 \][/tex]